MIT Scientists Create a More Efficient Solar Cell by Using Quantum Dots and Nanowires

A team of researchers at MIT have developed a more efficient photovoltaic solar cell using particles known as quantum dots. The benefit of using quantum dots is that they can be produced cheaply, and the solar cells can be manufactured at room temperature, unlike silicon and other PV materials, which require high-temperature processing. Using a new technique, the scientists embedded the quantum dots in a ‘forest of nanowires,’ which will help the team to achieve higher efficiency ratios.

There’s at least one serious advantage to using quantum dot-based PVs over other materials: They can absorb light over a much wider range of wavelengths than conventional solar cells. By using zinc oxide nanowires, the team was able to create a solar cell that’s thick enough to absorb light efficiently, but also thin enough to extract a charge.

The new design produces a 50-percent increase in the current generated by the solar cell and a 35-percent increase in overall efficiency of the cell, according to MIT doctoral student Joel Jean. Although the new solar cells are still in the testing phase, the researchers are optimistic that the breakthrough could lead to new, cheaper kinds of highly-efficient solar devices. Tests have already produced efficiencies of about 5 percent — among the highest ever reported for a quantum-dot solar cells — and the researchers have suggested that the devices’ may be able to achieve overall efficiency of more than 10 percent.